It is known to generally provide a check valve fitted to the mouth of a water bottle to prevent or reduce spillage of water while inverting the water bottle that is used in an invertible type water cooler and dispenser. The known check valves designed for this purpose were to be used in association with water bottles made of glass and are not suitable to be used on water bottles, such as now found on the market, and which are made of synthetic resin by a vacuum-forming process.